Pump unit for impact tool



March 26, 1946.

c. F. WARREN "ET AL PUMP UNIT FOR IMPACT. TOOL Filed May '13, 1942 4 Sheets-Sheet 1 INVENTORSL Marie/Z) u Fl- March 1946. c. F. WARREN ETAL 2,397,174

YUM? UNIT Foix mmcm' TOOL Filed May 15, 1942 4 Sheets-Sheet 2' [llll \Iill.

M r 26, 194 c. F. WARREN ETAL ,17

- PUMP UNIT FOR IMPACT TOOL v Filed May @s, 1942 4 Shets-Sheet. 3

. 4 Sheets-Shea; 4

' Filed May '13, 1942 "c. F. WARREN ETAL PUMP UNIT FOR IMPACT TOOL March 26, 1946.

Patented Mar. 26, 1946 PUMP UNIT FOR IMPACT TOOL Charles F. Warren,. Milwaukee, and Karl F. Kuehn, Wauwatosa, Wis., assignors, by mesne assignments, to Hydraulic Impact Tool Company, Milwaukee, Wis., a limited partnership oi.

Wisconsin Application May 13, 1942, Serial No. 442,730

(Cl. fill-54.5)

6 Claims.

This invention relates to improvements in power tools of the impact operated type, and it is particularly concerned with the pump or impact prof ducing unit of such a tool. Theobjects cf the invention include First, to provide a new and improved hydraulically actuated impact tool system.

Second, to provide a pump unit for hydraulically actuated impact tools which shall be relatively simple and economical to manufacture and to repair.

Third, to provide a'pumping device comprising three principal parts, namely, a housing which serves also as a reservoir for fluid, a pump assembly supported in the housing and removable as a unit therefrom, and a drive shaft with its operating eccentrics and bearings also removable as a unit from the housing.

Fourth, to provide a pump having a compound piston which operates simultaneously as an impact producing element and as a make-up pump to maintain the impact transmitting column of fluid at all times. i I

Fifth, to provide a pressure regulator which is included in the pump assembly within the housing and which cooperates with the make-up pump to keep the hydraulic column under a predetermined initial pressure.

Sixth, to provide a pumping device for a hy-v draulic transmission system which employs a column of liquid under pressure and a pressure regulator having a spring-pressed piston operable to maintain liquid under a predetermined pressure, and to provide a drain port for the liquid column controlled and normally covered by such piston, and means for shifting the piston at will to a position at which it uncovers the drain port for dis-- sipating the hydraulic pressure of the column, rendering it temporarily ineffective for transmiss1on purposes.

Other objects and advantages will appear from the following specification taken in connection with the accommpanying drawings, in which:

Fig. l is a perspective view of a pump unit em bodying this invention,

Fig. 2 is an end elevation of the pump unit.

Fig. 3 is a vertical sectional view taken substanillustration of an implement connected to the Fig. 8 is a detail section at the same plane as Fig. 6, showing the pressure regulator piston'i'n released position for draining the hydraulic column.

While the invention is susceptible of various modifications and alternative constructions, the embodiments shown in the drawings and described hereinafter are by way of preferred illustration only, and it is not intended that the invention be limited thereto or thereby, but it is the intention to cover all modifications andalternative constructions falling within the scope of the invention as defined by the claims.

Impact driven tools of the character to whic this invention relates are in the nature of hammers, drills and tamper-s, which are similar in function to corresponding pneumatically driven tools. However, such tools of the pneumatic type require the provision of an air compressor unit accompanied by an internal combustion motor or other prime mover of substantial power, whereas the combination of an impact pump'a'nd an impact driven tool directly connected to the pump by means of a hose line, which confines a continuous column of fluid extending from the pump to the tool, constitutes a much more efiicient mechanism which employs only a fraction of the power for driving the pump and thus operating the tool. The pump unit which is the subject of this invention is intended for use in such a combination, although it should be understood that it may serve to operate hydraulically driven motor devices in a wide range of mechanisms. It is of the same general character as the pumps shown in the copending application of Charles F. Warren. Serial No. 377,271, filed February 3, 1941, and in Patent No. 2,260,268, issued to Charles F. Warren and William R. Smith, dated October 21, 1941, and. it is intended for use in combination with impact driven tools and other mechanisms similar to those described in said application and patent.

The operating elements of the pumping unit are mounted in the housing I which serves also as a reservoir for the hydraulic fluid and which is seen in Fig. l as of substantially mctangular form except that the top wall 2 and one end wall 3 are connected by a curved portion 5 substantially concentric with the axis of the drive shaft 5. This shaft extends through a hollow boss 6 in one side wall of the housing, and. the boss 6 provides a pocket or recess 6 which seats the roller bearing 1 for the shaft together with a packing element 8. A circular opening 9 in the opposite side wall of the housing is large enough to permit insertion or Withdrawal of the shaft with its driving'eccent-rics. l 4], Hlt'ogether with the; bearing assembly I; and this opening- 9 is closed by a cover plate ll, which includes an inwardly open pocket or recess I I to support a roller bearm ing l2 for the inner end of the shaft. 5. .Each. of the eccentrics I0 carries a ring I3 confined between a flange [0 and a retainer ring Ni -with interposed bearing rollers, M; so that the eccentric may turn freely within 'tliering [3: Thus in the process of assembly, the shaft 5; with' its. bearings 1 and I2 in place and with its eccentrics l3 fitted with their rings I4, maybe inserted as: a unit through the opening 9, and its mounting in the housing will be completed by application of 7 TheTpumping unit proper iscontained ina cast- I ing l-fi having a circular: inner endportion H:

which. fits snugly'into=a.circular opening Lain; a.- diaphragm or partition wall l9 extending across; the. housing I-, as-seen-.in Figs; 3- and 4-. Thisprovides support for the. inner endrofithecasting. t6.-

and, locates the closedends ofthe pistons; 21]; inoperative relationzto-th'erings E3 on the driving eccentrics l'0, l-Gz At its:outer-end the pump casting LE is formed. with afiange 21- having a: circular shoulder 2-2 whichfits into a circular.

opening 23 in the end wall. E le-of, the housing t.

The pumping unit is secured. inlplaceby: screws. 25 extending through said flange; into the. end Wall. 24- adjacent its opening. 23; Thus. the in sertion of.- the unit IS; with the:- pistons- 20 andother" operative. par-ts alreadyassembled in. it; completes. the assembly; of the pumping device.

Each; ofthe. pistons 2t. ishollow and. open at. one. end toaccommodatea-spring 2-6 which reacts. againstthe endwall of a chamber 21', formedin, the; casting L6; and: each; piston. includes a larger. portion: Ell and. aslightly. smaller portion Zeb-thecasting It being formed with correspondingbores; us andv lfi in: whichthese; portions of the.- piston reciprocate-respectively; The bore. Ni communi cates directly with. the chamber 2.1,, and said: chamber terminates.- in a-. threaded opening intowhichthe terminal 287 of'theflexible hose 29.:is:

secured,.as seen in Fig. 4a. Thus, whenthe hole low' piston 20 and chamber 2'!r andhose line 29: are filled: with; fluid the: reciprocatory movements; of the piston are transmittedlongitudinally by thecolumn.- ot fluid to a toolor otherv apparatus. withwhich the hose Z9 is. connected: as shown: somewhat diagrammatically'in Fig.1 5:

In. Fig. 5' there isillustrated; an: implement 93 ot the. type disclosed. in said, co-pending. ap-plicae tion, of Charles Warren, Serial No. 37-'7;,27l=. This implement consists generally of; a. barrel 9 I witha. striking plunger 92 reciprocablymounted therein and havingits. movement. in one. direction opposed bya coilspring 93-. The-conduit. communicates witha chamber 94; in one; end ofthe:barre1, this chamber in-turn; communicating with acylinder 9.5 in which a conduit terminalor closure. 95;. in the. form of apiston,v reciprocates: Thea conduit 29 is normally provided with, sufiia cient fluid to. initially compress thewspring; 9.3 to

an extent sufficient to place the fluid column under a predetermined static or normal pressure; It is to be understood, as disclosed in said co-pend-' ing application and said Warren and Smith patent, that. the column of liquid in the conduit 29 reciprocates as a rigid body when the corresponding-piston 20 is reciprocated; the liquidcol umnbeing'movedin one direction by the impact produced by the piston 20 and being moved in return direction by the coil spring 93;

The. lower portion of the housing I serves as a'rese'rvoirfor the fluid which will be maintained always'at. a level considerably above the lower end oi 'the supply'pipe 30 which depends from the piunp casting; lfi andis secured therein by a gland 31- which also supports the valve seat 32 .for a ball check valve 33'- normally seated by its spring 331 The. checkvalve 33 controls access to an annular. passage 35 formed in the casting 16 at the junction of thebores lfi and 16 The shoulder 2090f thepiston Zllwhich defines the outer end-pf thejlarger portion-20 operates asasecondary piss.

shoulder 2i! ofthe piston. 1 Then,.up.on-.the return stroke of the piston, the shoulder 20 forces the,

fluidpasta secondcheckvalve 3.6. andthrough a passage37- whichleadsinto the. regulator, chamber 38. This chamber. isprovidedwith a movable'. wall orpiston 39 backed up by a spring Mlfor maintains ing the liquid under a definite pressure at. all. times. When the pressure in the. chamber 38 is sufficient to force the piston 39 back to a. point,

at which it uncovers a relief port 41' in thewallof the chamber. 38-, any excess of liquid thereafter supplied by the pumpingactioIrof-the secondary piston 26 will escape through: the. port, 41- and; through the connected passage 52 which dis,-

charges the fluid, preferably oil,,directly onto'the' eccentric rings I 3 so that'it serves-for lubricating them and the endsof the pistons 29'; Eventually the-oil returns by gravity to the lower-portion-of thehousing I, which actsas areservoir therefor:

With a quantity of fluid thus held in the chamber 38 'under pressure suppliedby-thespring E0, theoperating columnof liquid'ezitending from the. piston 20' through the chamber 2'! and" hose 29' is maintained at all timesand any'loss of fluid therein is replenished by way of an injector duct 43' which connects with the passage 3? and opens into thesmaller bore It at a terminal. port which will be uncovered when thesmaller portion duringieach; reciprocation of they piston 20; the

bore: t6? and: the chamber 21: are placed income munication with: the pressure regu-lating'chamber 38- by'way-of; the. duct:.t.3.. If thelossof fluidjin the operating line is not Wholly replaced: by; a

g e. injection of? fluid: from; the chamber: 38 through. this duc 43;, it will. be: quickly made up bythe: rapidly repeated. injections: which will; 00,-.

- cur with each successive; piston strokeuntil the pressureisaequalized with that inth chamber 38. The; fluid thus transferred from the chamber- 3.3. will be promptly replaced by the action of -the-v secondary piston 2B-drawi-ngliquid f-romtheareserve supply in. the lower'portion. of the housing:

I and transferring it through the passage 31 to the chamber 38. The pressure spring 40 is seated against a flange or button 44 which may be regulated by means of a threaded stud 45 to secure the desired tension in the spring 40 and the resultant pressure upon the liquid at 38, and preferably the slotted end 46 of the stud 45 is enclosed in a removable cap 41 to prevent tampering or accidental change in its adjustment.

To interrupt or terminate the operation of the tool or apparatus which is driven by the impact transmitted through the hose line 29, it is only necessary to open a by-pass valve 48 which permits escape of the liquid from the chamber 21 through a drain passage 49 and its outlet portion 50, thus dissipating the pressur in the hydraulic transmission line and allowin the liquid to be merely pumped around and around a by-pass circuit through the reservoir in the housing I. A hand wheel 48 is conveniently accessible outside the end wall 24 of the housing I for adjusting the valve 48. The shaft and its eccentrics I0, may continue to operate and reciprocate the pistons 26, so that the transmission of power will be resumed promptly upon closing of the valve 48, a few revolutions of the shaft 5. serving to replenish the oil supply in the chamber 21 by way of the supply pipe and injector duct 43, as already described.

In the construction herein illustrated, with the two eccentrics I0, [0 set 180 apart on the shaft 5, the mechanism is in the nature of a duplex pump with the two pistons 20, 28 operating alternately and thus transmitting separate impulses through the two hose lines 29 which are connected respectively to the two chambers 21. Preferably, each pressure line is provided with its individual regulator chamber 33, but the relief ports 41 for these chambers open into a common passage M through which they communicate with a single discharge passage 42 which is conveniently formed in the casting it between the passages 31, as seen in Fig. 5.

The unitary casting IS in which the pumping mechanism is carried is so designed that all bores and passages can be very conveniently completed by simple drilling and tapping operations. The chamber 2! are cored in the casting and the bores 20 and 20 are readily formed by drilling and reaming, if desired. Passages such as those at 43 and 49 are readily drilled and then closed by screw plugs, as shown at 43 and 49 and other finishing operations are equally simple. Preferably, the circular flange I! and the circular shoulder 22 are coaxial so that they can be finished in a single turning operation and the openings in which they are to fit in the housin I can also be finished in a single setting of the machine on which the work is done. Therefore, it is possible to manufacture the pumping unit rapidly and economically, and its installation in the housing I is an extremely simple matter, as already described.

In operation it is most convenient to use oil for the impact transmitting medium and to employ the same oil for lubrication of the mechanism; accordingly, the web or partition 19 is formed with an opening in its lower portion which affords communication between the space in the housing directly under the drive shaft 5 and the space extending below the pump cylinder casting l6. Preferably this opening is covered by a screen 5|. A screw plug 52 is removable from the top wall above the shaft 5 for adding oil as required. Although the feed tubes 30 and check valve assemblies 3|, 32, 33, 34 can be originally attached to the cylinder casting I6'and entered with it through the opening 23, it may be desirable to remove these parts occasionally without withdrawing the cylinder units and to facilitate this the bottom wall of the housing is formed with threaded openings directly below the tubes 30,

these openings being normally closed by screw plugs 53, as shown in Fig. 4. x:

Figs. 6, 7 and 8 illustrate a modified construction in which the draining function of the bypass port 49 and valve 48 is accomplished by a slight change in the structure associated with the pressure regulator. Instead of having the adjusting screw for the pressure spring 40 secured in a threaded bushing which is fixed in the end wall 2| of the cylinder casting ['6 (as shown in Fig. 4) the regulator screw 65, shown in Fig. 6, is

engaged in the threaded bore of a plug 60 which is in the form of a sleeve so that the abutment disk or button 44 for the spring 40 is carried and guided within it. The sleeve or plug 60 is slidably fitted in the outer end of the regulator cylinder 33 with the spring 40 reacting between the button 44 and the regulator piston 66. Thus the pressure of the spring is transferred to the plug 60. The plug itself is normally locked in position by means of a bifurcated lever 63 having arms which'bear against shoulders 69 formed by cutting flats Til on two sides of the end portion of the plug 60. The lever is fulcrumed at ll in fixed brackets 12 projecting from the end wall 13 of i the cylinder casting which is modified to this extent as compared with the structure shown in Fig. 4. A latch dog 14 engages the shoulder 15 on the lever member 68 to restrain it against rotation about its fulcrum pin H; thus as long as the latch 14 remains in looking engagement with the lever '58, it holds the plug 60 in position to maintain the regulator spring 40 under compression corresponding to the hydraulic pressure acting against the piston 66. As in the structure of Fig. 4, an increase in the hydraulic pressure forces the piston 66 back against the spring 40 sufficiently to uncover the relief port 4i to prevent the hydraulic pressure exceeding the predetermined value correspondin to the adjustment of the pressure screw 65. I

But in addition to the relief port 4!, the cylinder casting I6 is provided with a drain port 88' and a supplemental passage 8|, both of which are normally covered by the piston 66. If it is desired to interrupt the operation of the tool or device to which the hydraulic conduit is connected by way of the hose 29, the latch 14 is released so as to allow the bifurcated lever 68 to swing outwardly as shown in Fig. 8, thus permitting the hydraulic pressure to force the piston 66 back far enough to uncover the drain port 8!! and the supplemental passage 8! which leads directly from the chamber 21. This promptly results in dissipating the pressure in the hydraulic conduit and thus rendering the operation of the pump ineffective for the time being for transmitting impacts through the hydraulic column.

' Since the pressure of the locking shoulder against the latch dog '14 is rather heavy, and since preferably the engaged faces ,of these parts are the: drain portfw as.v described. It may heanoterl that the. outward. swing of the; arms; [iii is; link by encounterof a; flat face 83 of the" lever: withthe fiat side- 8 9 of? the. latch dog: 1:4, as shown; in; Figi 8 that at this. limit. of their outward swing the arms of, the'lever remain in contact with. the. shoulders 59 of the-plug 68 so asto provent escape of the latter'fromthe end oi the cylinder 38. I r

We. claim as our invention:

. 1. Ina hydraulic:- impact-transmitting system which includes a conduit confining a rigid reciprocable column of liquid with a work-delivering piston closing one end of the conduit andspring means backing said: piston, an impactproduci'ng unit comprising ahousing,a rotary; shaft journaled thereinand: extending outside the; housing for connection with. a driving means, an impact pump and a make-up pump with piston. means for said pumps operatively engaged with. said shaft and all contained within said housing, the impact pump constituting; theother.-

' chamber comprising a cylinder disposed Within the housing with a piston in said cylinder constituting a movable wall thereof, said yielding means comprising'a spring reacting against. the piston, a plug 'slida'bl'y disposed in said cylinder engaging one end of the spring and normally holding it compressed against the piston to maintain a predetermined hydraulic pressure in the system, a drain passage for the conduit extending to said cylinder, said passage opening directly into the housing and being normally closed by the regulator piston therein, and looking means holding the plug and piston in such normal position but releasable at will to relieve the-spring pressure on the piston, permittingthe same to open said drain passage and release the. liquid from the conduit through said passage and into the housing, thereby dissipating the pressure or" the liquid column.

2. In a hydraulic impact-transmitting system which includes a conduit confining a'rigid re:- ciprocable column of liquid with a work-delivering piston closing one end of the conduit and spring means backing said piston, an impactproducing unit comprising a housing, a rotary shaft journaled therein and extending outside thehousing for connection with a driving means, an impact pump and a make-up pump with piston means for said pumps operatively engagedwith said shaft and all contained within said housing, the impact pump constituting the other end of said conduit, the housing containing-a supply of liquid, an intake passage in the housing from said supply to the make-up pump, a

the impact pump. therein. and cmistitutingia; per-i tion of the said conduit, said regulating chant-F,-

her comprising a. cylinderdisposed; With-in:

housing-s with a piston in said. cylinder constitut ing a movable wall thereof, said yielding means comprising a spring reacting: against the piston;

a plug slid'ably disposed in said cylinder'engag ing one endof the spring and normally holdiing it compressed against the piston to main tain a predetermined hydraulic pressure in the system, drain passages for the conduit and for the regulating chamber both discharging direct-T 1y into the housing but normally closed by" the regulator piston therein, and locking means hold ing the plug and piston in normal position-hut releasable at will to relievethe spring pressure on the piston, allowing said piston to uncover.

the drain passages and release liquid from the" conduit and from the regulator chamber simul taneousl'y into the housing,v thereby dissipating the' pressure of the liquid. column.

3. In a hydraulic impact-transmitting systein V duit,. together. with a pressure-regulating chain-=1 1 her comprising. a cylinder with a. piston therein, and. a-spring opposing movement of the pawn;-

in response to the hydraulic pressure, a. plug, in.

the-regulator cylinder with abutment means engaging one end. of: the springnormally holding. it compressed against. the piston. to maintaina predetermined hydraulic pressure in the system a drain passage for the conduit, normally-closed by said regulator piston, and locking meanshold' ing the plug and piston. in, such normal. position.

but releasable at will. to relieve. the spring pres,-

sure on the piston andrpermit ittouncoven said,

drain port, thereby dissipating the pressure. of!

the liquid column, said lock-ing means comprising a lever fulcrumed adjacent the outer end.- of said plug with the arm of the lever bearing against'atransverse shoulder of: the plug, and a pivoted latchdog releasably restrainingthe lever against movement about its: fulcrum.

lJIn the combination defined; inclaim .35; means limiting the swing ofthe lever when re.- leased to prevent escape-of. the plug from. the: regulator cylinder. 5 In: a hydraulic" impact-transmitting system}. a pump comprisingv a cylinder having a: larger. bore and an adjacent" smaller; bore with an: arr-' nular channel of relatively limited axial extent; and of greater diameter than the larger bore:

formed inthe cylinder between the adjacent ends of said bores, a unitary pistoni having a larger? portion fitted in the larger cylinder bore andiai smaller portion fittedv in the: smaller bore;. said! piston having an annular shoulder defining the: end ofits larger portion adjacent its smaller portion, means engaging the opposite end of saidl larger portion to reciprocate the piston, intake and delivery passages communicatingqwith said: annular channel with check valves controlling said passages, a hydraulic transmission conduit: in direct communication with the smaller bore,v the said intake passage leading" from a supply otliquid and the delivery passage furnishing liquid to said conduit with the annular shoulder of'the piston reciprocating in: saidlarger bore towards and from the annular channel and thus functi'one ing as a make-up pump when the piston is reciprocated.

6. In a hydraulic impact-transmitting system,-

a pump comprising a cylinder having a larger bore and an adjacent smaller bore with an annular channel of relatively limited axial extent and of greater diameter than the larger bore formed in the cylinder between the adjacent ends of said passagescommunlcatmg with said annular channel with check valves controlling said passages, a hydraulic transmission conduit in direct communication with the smaller bore, the said intake passage leading from a supply of liquid and the delivery passage leading into the smaller bore of the cylinder through a port which is uncovered by the smaller portion of the piston at the commencement of theworking stroke of the piston, whereby the annular shoulder of the piston then acts as a make-up pump to supply liquid to the conduit from said annular channel of the cylinder.

CHARLES F. WARREN. KARL F. KUEHN. 

